Question

what is the big bang theory?

Answer 1

The Big Bang theory is the prevailing cosmological model for the universe from theearliest known periods through its subsequent large-scale evolution.[5][6][7] The model accounts for the fact that the universe expanded from a very high density and high temperature state,[8][9] and offers a comprehensive explanation for a broad range of phenomena, including the abundance of light elements, the cosmic microwave background, large scale structure and Hubble's Law.[10] If the known laws of physics are extrapolated beyond where they have been verified, there is asingularity. Some estimates place this moment at approximately 13.8 billion years ago, which is thus considered the age of the universe.[11] After the initial expansion, the universe cooled sufficiently to allow the formation of subatomic particles, and later simple atoms. Giant clouds of these primordial elements later coalesced through gravity to form stars and galaxies.Since Georges Lemaître first noted, in 1927, that an expanding universe might be traced back in time to an originating single point, scientists have built on his idea of cosmic expansion. While the scientific community was once divided between supporters of two different expanding universe theories, the Big Bang and the Steady State theory, accumulated empirical evidence provides strong support for the former.[12] In 1929, from analysis of galactic redshifts, Edwin Hubble concluded that galaxies are drifting apart; this is important observational evidence consistent with the hypothesis of an expanding universe. In 1965, the cosmic microwave background radiation was discovered, which was crucial evidence in favor of the Big Bang model, since that theory predicted the existence of background radiation throughout the universe before it was discovered. More recently, measurements of the redshifts of supernovae indicate that the expansion of the universe is accelerating, an observation attributed to dark energy's existence.[13] The known physical laws of nature can be used to calculate the characteristics of the universe in detail back in time to an initial state of extreme density and temperature.

Answer 2

Answer:

The Big Bang theory was proposed to explain the origin of universe. According to this theory, the origin of universe took place due to a single huge explosion in the space due to which the various galaxies were formed in it.

Its various postulates were :

• The earth formed about 4.5 billion years back.
• There was no atmosphere on early earth.
• Water vapour, methane, carbon dioxide and ammonia were released from the molten mass which came out of earth due to volcanic eruptions.
• The UV rays broke up water into Hydrogen and Oxygen.
• The ozone layer formed from oxygen slowly
• Water vapour condensed fell down as rain, to fill the depressions and form oceans.